A bushfire in the Blue Mountains National Park was sparked by a father and son who allegedly torched clandestine meth labs the day police were supposed to raid the multimillion-dollar operation.

NSW Drug Squad police charged Peter Martin, 55 and Jim Martin, 27, both of West Hoxton, on Sunday night after two laboratories deep in bushland 60 kilometres west of Camden were set on fire last Wednesday.

We don't know what spooked them, we don't know what tipped them off to light the fire. Obviously they've become aware of our investigation but we are not sure how

Fire quickly spread through the Blue Mountains National Park and was only extinguished on Sunday night after six aircraft and dozens of Rural Fire Services volunteers fought the blaze.